Generate a SHA-256 hash with this free online encryption tool. To create a SHA-256 checksum of your file, use the upload feature. To further enhance the security of you encrypted hash you can use a shared key. Your file is currently uploading. The input string encoding is expected to be in UTF-8. A is a key-dependent, one-way hash function that allows only specific recipients (symmetric key holders) to access the message digest. A method of encryption that requires the same secret key to encipher and decipher the message is known as encryption. DES uses a(n) -bit block size. Generating end-user keys, revoking.
HMAC(Hash-based message authentication code) is a message authentication code that uses a cryptographic hash function such as SHA-256, SHA-512 and a secret key known as a cryptographic key. HMAC is more secure than any other authentication codes as it contains Hashing as well as MAC.
Below is a free online tool that can be used to generate HMAC authentication code. We can generate hmac-sha256 as well as hmac-sha512 code with it.
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Usage Guide - HMAC-SHA256 Online Tool
First, enter the plain-text and the cryptographic key to generate the code. Then, you can use select the hash function you want to apply for hashing. The default is SHA-256. Then you can submit your request by clicking on the compute hash button to generate the HMAC authentication code for you.
By default, the output is in plain-text format but you also have an option to get the output in Base64 format. Below is a screenshot of the usage:
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Other Free ToolsDBMS_CRYPTO provides an interface to encrypt and decrypt stored data, and can be used in conjunction with PL/SQL programs running network communications. It provides support for several industry-standard encryption and hashing algorithms, including the Advanced Encryption Standard (AES) encryption algorithm. AES has been approved by the National Institute of Standards and Technology (NIST) to replace the Data Encryption Standard (DES).
See Also:
Oracle Database Security Guide for further information about using this package and about encrypting data in general.
This chapter contains the following topics:
Using the DBMS_CRYPTO SubprogramsOverviewDBMS_CRYPTO contains basic cryptographic functions and procedures. Cd key generator for games. To use this package correctly and securely, a general level of security expertise is assumed.
The
DBMS_CRYPTO package enables encryption and decryption for common Oracle datatypes, including RAW and large objects (LOB s), such as images and sound. Specifically, it supports BLOB s and CLOB s. In addition, it provides Globalization Support for encrypting data across different database character sets.
The following cryptographic algorithms are supported:
Block cipher modifiers are also provided with
DBMS_CRYPTO . You can choose from several padding options, including PKCS (Public Key Cryptographic Standard) #5, and from four block cipher chaining modes, including Cipher Block Chaining (CBC).
Table 40-1 summarizes the
DBMS_CRYPTO package features.
Table 40-1 DBMS_CRYPTO Features
The
DBMS_CRYPTO package replaces DBMS_OBFUSCATION_TOOLKIT , providing greater ease of use and support for a range of algorithms to accommodate new and existing systems. Specifically, 3DES_2KEY and MD4 are provided for backward compatibility. It is not recommended that you use these algorithms because they do not provide the same level of security as provided by 3DES, AES, MD5, SHA-1, or SHA-2.
Security Model
Oracle Database installs this package in the
SYS schema. You can then grant package access to existing users and roles as needed.
Datatypes
Parameters for the
DBMS_CRYPTO subprograms use these datatypes:
Table 40-2 DBMS_CRYPTO Datatypes
Algorithms
The following cryptographic algorithms, modifiers, and cipher suites are predefined in this package.
Table 40-3 DBMS_CRYPTO Cryptographic Hash Functions
Table 40-4 DBMS_CRYPTO MAC (Message Authentication Code) Functions
Footnote 1 Complies with IETF RFC 2104 standard
Table 40-5 DBMS_CRYPTO Encryption Algorithms
Table 40-6 DBMS_CRYPTO Block Cipher Suites
Footnote 1 See Table 40-5, 'DBMS_CRYPTO Encryption Algorithms'
Footnote 2 See Table 40-7, 'DBMS_CRYPTO Block Cipher Chaining Modifiers'
Footnote 3 See Table 40-8, 'DBMS_CRYPTO Block Cipher Padding Modifiers'
Table 40-7 DBMS_CRYPTO Block Cipher Chaining Modifiers
Table 40-8 DBMS_CRYPTO Block Cipher Padding Modifiers
Restrictions
The
VARCHAR2 datatype is not directly supported by DBMS_CRYPTO . Before you can perform cryptographic operations on data of the type VARCHAR2 , you must convert it to the uniform database character set AL32UTF8, and then convert it to the RAW datatype. After performing these conversions, you can then encrypt it with the DBMS_CRYPTO package.
See Also:
'Conversion Rules' for information about converting datatypes.
Exceptions
Table 40-9 lists exceptions that have been defined for
DBMS_CRYPTO .
Table 40-9 DBMS_CRYPTO Exceptions
Operational NotesWhen to Use Encrypt and Decrypt Procedures or Functions
This package includes both
ENCRYPT and DECRYPT procedures and functions. The procedures are used to encrypt or decrypt LOB datatypes (overloaded for CLOB and BLOB datatypes). In contrast, the ENCRYPT and DECRYPT functions are used to encrypt and decrypt RAW datatypes. Data of type VARCHAR2 must be converted to RAW before you can use DBMS_CRYPTO functions to encrypt it.
When to Use Hash or Message Authentication Code (MAC) Functions
This package includes two different types of one-way hash functions: the
HASH function and the MAC function. Hash functions operate on an arbitrary-length input message, and return a fixed-length hash value. One-way hash functions work in one direction only. It is easy to compute a hash value from an input message, but it is extremely difficult to generate an input message that hashes to a particular value. Note that hash values should be at least 128 bits in length to be considered secure.
You can use hash values to verify whether data has been altered. For example, before storing data, the user runs
DBMS_CRYPTO.HASH against the stored data to create a hash value. On returning the stored data, the user can again run the hash function against it, using the same algorithm. If the second hash value is identical to the first one, then the data has not been altered. Hash values are similar to 'file fingerprints' and are used to ensure data integrity.
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The
HASH function included with DBMS_CRYPTO , is a one-way hash function that you can use to generate a hash value from either RAW or LOB data. The MAC function is also a one-way hash function, but with the addition of a secret key. It works the same way as the DBMS_CRYPTO.HASH function, except only someone with the key can verify the hash value.
MACs can be used to authenticate files between users. They can also be used by a single user to determine if her files have been altered, perhaps by a virus. A user could compute the MAC of his files and store that value in a table. If the user did not use a MAC function, then the virus could compute the new hash value after infection and replace the table entry. A virus cannot do that with a MAC because the virus does not know the key.
About Generating and Storing Encryption Keys
The
DBMS_CRYPTO package can generate random material for encryption keys, but it does not provide a mechanism for maintaining them. Application developers must take care to ensure that the encryption keys used with this package are securely generated and stored. Also note that the encryption and decryption operations performed by DBMS_CRYPTO occur on the server, not on the client. Consequently, if the key is sent over the connection between the client and the server, the connection must be protected by using network encryption. Otherwise, the key is vulnerable to capture over the wire.
Although
DBMS_CRYPTO cannot generate keys on its own, it does provide tools you can use to aid in key generation. For example, you can use the RANDOMBYTES function to generate random material for keys.
When generating encryption keys for DES, it is important to remember that some numbers are considered weak and semiweak keys. Keys are considered weak or semiweak when the pattern of the algorithm combines with the pattern of the initial key value to produce ciphertext that is more susceptible to cryptanalysis. To avoid this, filter out the known weak DES keys. Lists of the known weak and semiweak DES keys are available on several public Internet sites.
See Also:
Hash Generation Requires Secret Key Card
Conversion Rules
Examples
The following listing shows PL/SQL block encrypting and decrypting pre-defined '
input_string ' using 256-bit AES algorithm with Cipher Block Chaining and PKCS#5 compliant padding.
Summary of DBMS_CRYPTO Subprograms
Table 40-10 DBMS_CRYPTO Package Subprograms
DECRYPT Function
This function decrypts
RAW data using a stream or block cipher with a user supplied key and optional IV (initialization vector).
Pragmas
Parameters
Hash Generation Requires Secret Key Of The World
Table 40-11 DECRYPT Function Parameters
Usage Notes
DECRYPT Procedures
These procedures decrypt
LOB data using a stream or block cipher with a user supplied key and optional IV (initialization vector).
Pragmas
Parameters
Table 40-12 DECRYPT Procedure Parameters
ENCRYPT Function
This function encrypts
RAW data using a stream or block cipher with a user supplied key and optional IV (initialization vector).
Pragmas
Parameters
Table 40-13 ENCRYPT Function Parameters
Usage Notes
ENCRYPT Procedures
These procedures encrypt
LOB data using a stream or block cipher with a user supplied key and optional IV (initialization vector).
Pragmas
Parameters
Table 40-14 ENCRYPT Procedure Parameters
Usage Notes
See 'Conversion Rules' for usage notes about using the
ENCRYPT procedure.
HASH Function
A one-way hash function takes a variable-length input string, the data, and converts it to a fixed-length (generally smaller) output string called a hash value. The hash value serves as a unique identifier (like a fingerprint) of the input data. You can use the hash value to verify whether data has been changed or not.
Note that a one-way hash function is a hash function that works in one direction. It is easy to compute a hash value from the input data, but it is hard to generate data that hashes to a particular value. Consequently, one-way hash functions work well to ensure data integrity. Refer to 'When to Use Hash or Message Authentication Code (MAC) Functions' for more information about using one-way hash functions.
This function applies to data one of the supported cryptographic hash algorithms listed in Table 40-3.
Pragmas
Parameters
Table 40-15 HASH Function Parameters
Usage Note
Oracle recommends that you use the SHA-1 (Secure Hash Algorithm) or SHA-2 because it is more resistant to brute-force attacks than MD4 or MD5. If you must use a Message Digest algorithm, then MD5 provides greater security than MD4.
MAC Function
A Message Authentication Code, or MAC, is a key-dependent one-way hash function. MACs have the same properties as the one-way hash function described in 'HASH Function', but they also include a key. Only someone with the identical key can verify the hash. Also refer to 'When to Use Hash or Message Authentication Code (MAC) Functions' for more information about using MACs.
This function applies MAC algorithms to data to provide keyed message protection. See Table 40-4 for a list of MAC algorithms that have been defined for this package.
Pragmas
Parameters
Table 40-16 MAC Function Parameters
RANDOMBYTES Function
This function returns a
RAW value containing a cryptographically secure pseudo-random sequence of bytes, which can be used to generate random material for encryption keys. The RANDOMBYTES function is based on the RSA X9.31 PRNG (Pseudo-Random Number Generator).
Pragmas
Parameters
Table 40-17 RANDOMBYTES Function Parameter
Usage Note
The
number_bytes value should not exceed the maximum length of a RAW variable.
RANDOMINTEGER Function
This function returns an integer in the complete range available for the Oracle
BINARY_INTEGER datatype.
Pragmas
RANDOMNUMBER Function
This function returns an integer in the Oracle
NUMBER datatype in the range of [0.2**128-1].
Pragmas
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